got a problem with my 450 , suddenly it will only start to hover when throttle is at 3/4 , then not much after that , how can I get it to start sooner , tx set at factory esttings. checked all parts on heli seems ok ..

You might have a pitch problem, as in you are at negative pitch when your throttle is at half stick, so you are having to get to 60-70% before you even get any positive pitch in the blades. Unplug the motor or make sure throttle hold is on and get down where you are eyeballing the blades. Move stick to half throttle and see if the pitch is even. If its Negative you need to adjust the servo linkages to lengthen them until its level at 50% stick. If in fact it's already at zero pitch you probably need to check your transmitter pitch curve settings and make sure you have a little more pitch than what's in the manual at each point. It will hit the ground pretty hard at half stick with the recommended settings in the manual so you to add a little pitch in the low part if the curve.

just checked it all over again and still the same as before , will try and adjust the curve settings, as you suggested,,,I think that I have looked at this problem about 2o times might have to pay my local hobbie shop to see if they can fix it , thanks anyway ..

1. Head speed is reduced for some reason. (a few things can cause this issue as well).
2. Blade pitch is wonky. The blade pitch should be at 0 when you are at mid stick.

When ever you have an issue always think about when the last time it flew correctly and ask myself what has changed since then? Did I have a crash and during repairs not get something right? Did I accidentally, or on purpose, change a setting in the radio?

If you don't' have a pitch gauge you should really get one, they are very important tools to have. In the mean time an easy way to check your pitch at mid stick, like Kalashluvr said, unplug the motor so it won't spool up and plug in a battery. Fold both blades back so they are parallel to the boom. put your throttle at mid stick. The blades should be even with each other. If not then you don't have 0 pitch.

I have looked at this video at least 10 times thinking am I doing it the same , I think so but being new to heli, some of the terms I dont know , will look at again , and see what is different , all the settings are the same as the manual. thanks again